Semiconductor chips (or dies) are packaged and electrically connected to an external circuit to constitute an electronic device. When a semiconductor chip is packaged, the semiconductor chip is attached onto another semiconductor chip or a substrate, such as a printed circuit board (PCB), via interlayer adhesive layer, such as adhesive paste or adhesive film.
In a semiconductor package including the interlayer adhesive layer, if adhesion strength of the interlayer adhesive layer is insufficient, a crack or an exfoliation may occur at the bonding interface between adjacent layers during fabrication or usage of the semiconductor package, thereby causing a defect in electric connections between semiconductor chips or between a semiconductor and a substrate, and, in some cases, causing a fracture in the stacked structure of the semiconductor package. Recently, as semiconductor devices become miniaturized, a thickness of an interlayer adhesive layer as well as that of a semiconductor package are significantly reduced, and thus the interlayer adhesive layer may be more susceptible to an occurrence of cracks or exfoliations of bonding interfaces. However, regardless of the reduced thickness of the interlayer adhesive layer, a reliability of the semiconductor package is more tightly required, and thus it is necessary for the adhesive layer to have sufficiently reliable adhesive force. Therefore, a quantitative method of measuring adhesive force is desirable as a method of evaluating reliability of a semiconductor package.
MIL-812 is a standard for quantitative measurement. The MIL-812 is limited to measurement of adhesive force in the shear mode with respect to a device under test (DUT). During packaging process, interlayer exfoliation associated with the interlayer adhesive layer may be caused not only by shear stress, but also tensile stress. Therefore, in measurements based on MIL-812, causes of defects in interlayer adhesive layer of a semiconductor package may not be precisely detected.
To measure adhesive force of interlayer adhesive layer in the tensile mode, it is necessary to apply tensile force to interface of the interlayer adhesive layer. To this end, a jig for applying a load may be fixed to any one of stacked semiconductor chips, which are combined with each other such that interlayer adhesive layer is disposed between adjacent chips. Then, the jig fixed to a corresponding semiconductor chip may be pulled. However, it is difficult to firmly fix a jig onto a semiconductor chip having a small thickness or size. Furthermore, specific material properties of the interlayer adhesive layer, such as thickness or adhesive force, may be changed during fixation of the jig. Thus, precise and reliable measurement is difficult.